Greetings from Morocco

Ivo Freriks, 16 May 2014

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s2smodern

More and more cameras are no longer equipped with an anti-aliasing filter (AA filter), moiré filter or low-pass filter. Such a filter is often a thin, crystal plate (lithium niobate) in front of the sensor, which spreads the light that without an AA filter would hit just 1 pixel across multiple pixels. This suppresses moiré. The resolution of modern system cameras and SLR cameras is so high that in practice you don't notice if there's no filter any more, while you benefit from the higher sharpness and the higher signal-to-noise ratio that are consequences of the omitted filter. But there are exceptions.

We are often asked for practical examples of moiré. They are pretty rare: you can find it in photos of fabric (bridal dresses) or in shots of buildings (apartments). For the most part, nature makes little use of regular patterns, so that you have less trouble from it with nature photography. But there are exceptions.

In Erg Chebbi (عرق الشبي‎), Morocco, there's a great desert, with sand dunes up to 150 meters tall. In the sand, you sometimes see regular patterns. And then interference can arise, which makes moiré visible. Below, you can see a 100% partial enlargement of the RAW file, where the moiré color pattern is visible. The pattern is only visible on the foreground, not in the background. It's not color noise. With a local correction of moiré in Lightroom, it seems simple to correct. I feel like you would, just as with saturation, move the slider to the left to remove moiré, but it's to the right. That works outstandingly. You don't see it anymore.

With Camera Review Stuff I hope to make a modest contribution to the pleasure that you get from photography. By testing cameras and lenses in the same way, evluating the results and weighing up the pros and cons, I hope to help you find the right camera or lens.